F150 LOW IDLE PROBLEM

I have a 2005 F-150 with 48,000 miles. My problem is my truck sputters out and cuts off on me when I slow down to make a turn, come to a stop or (especually) when I turn the a/c. My truck cranks right back up and my engine is not makiing any noises. I took it to a mechanic and the machine read that I have a low idle issue. Any ideas on what may cause have caused this and how it can be fixed